This invention pertains to forced hot air heating furnaces, and more particularly to a furnace flue gas draft inducer outlet box assembly, hereinafter referred to as inducer outlet box assembly, directly attached to the inducer housing outlet and having a plurality of openings individually connectable to a vent, thereby providing selective attachment of the vent to accommodate installation thereof, and for collecting and delivering a return flow of condensate from the vent, thereby preventing the condensate from flowing to the inducer motor assembly, and particularly the inducer fan or wheel.
Generally, in forced hot air heating furnaces of the noncondensing-type, the vent pipe or chimney liner is maintained at a temperature above the dew point of the flue gases to prevent condensation of the water vapor in the gases within the vent pipe or chimney liner, and thus to prevent condensate from returning to the furnace and damaging or hindering the operation of any parts, such as motor assemblies, switches and the like. This is accomplished by maintaining the hot flue gases at a temperature approximately 140.degree. F. above the flue gas water vapor dew point wherein the excess temperature heats the vent pipe or chimney liner above the flue gas water vapor's dew point. Should the vent pipe or chimney liner temperature decrease below the dew point, then the cooler temperature will cause condensation of the flue gas water vapor. Thus, in these types of furnaces, increased costs in heating, waste of heat energy, and decreased furnace heating efficiency result from maintaining the flue gases at relatively high temperatures to increase the temperature of vent pipes or chimney liners. In these types of furnaces, it is not uncommon to have furnace heating efficiencies in the range of 80% to 85% wherein the lost heating efficiency has been used to vent flue gases due to their natural buoyancy and maintain the vent pipe or chimney liner temperature above the dew point.
Increases in furnace heating efficiency have been accomplished by purposely lowering the flue gas's temperature and condensing as much of the flue gas water vapor as possible to recover a portion of sensible and latent heat therefrom. This is generally accomplished by including a condensing heat exchanger in the heat exchanger assembly and passing cool air to be heated over the condensing heat exchanger. In these types of condensing furnaces, furnace heating efficiencies higher than 90% are not uncommon.
One of the problems associated with condensing furnaces is that because the flue gases are at a temperature below the water vapor dew point due to the further cooling thereof in the condensing heat exchanger, further condensation of flue gas water vapor occurs in the vent pipe or chimney liner. This latter condensate can return to the furnace and damage or hinder operation of the inducer wheel and prevent flow of the flue gases through the heat exchanger assembly and vent pipe or chimney liner. Thus, the need exists of removing the condensate from the heating furnace prior to contacting the inducer motor assembly, and particularly the inducer wheel.
One problem associated with most furnaces, i.e., both condensing and noncondensing, occurs during the installation of the furnace. Specifically, most furnaces only permit attachment of the vent in one particular fashion. For example, the vent generally can only be connected in one manner of orientation through a top surface of the furnace or one of the side walls. Thus, where available space for installation is limited or of unusual floor design, the orientation and manner of connecting the vent is very important. For example, should a particular furnace be constructed such that the vent is only connected thereto through the left side panel, then a problem occurs when the installation space requires the vent to be connected through the right panel of the furnace. Generally, the only solutions available in a situation such as this is to face the furnace in the opposite direction so as to place the left connecting panel to the right side of the installation space or to increase the length of the vent so that it may be attached to the left panel of the furnace and routed to an exhaust opening disposed in the opposite side of the installation space. Turning the furnace around to face an opposite direction or to increase the length of the vent pipe are respectively undesirable from practical and cost effective aspects.